Vein catheters are usually inserted into the vein of a patient by means of a hollow needle which is then withdrawn to avoid damage to the walls of the vein. The catheter remains fixed in the patient and is then connected to a source of infusion liquid. Fixing can conveniently be effected by means of flaps on the catheter which are pressed against the skin and, for example, as described in German Offenlegungsschrift No. 1,929,050, are secured there with adhesive tape. It has been proposed that these flaps should be pivotable about the catheter so that they can be gripped and can thus facilitate insertion of the catheter. However, it is very expensive from a manufacturing standpoint to fit such pivotable flaps; and the presence of the flaps renders the satisfactory packing of the device more difficult. In addition, due to their relatively large surface area, the sterilization of such catheters, which is nowadays normally effected by irradiation, is generally more expensive than with devices having smaller surface areas.
Furthermore, when inserting the catheter it is a matter of considerable importance to ensure that the needle is correctly positioned in the vein in order to avoid damage to the walls of the vein and resulting pain to the patient. During insertion, it is generally desirable that the point of the needle should be maintained in the top or, more preferably, the bottom position when viewing the needle from its pointed end. The correct insertion of the needle is rendered difficult by the fact that the point of the needle is invisible after it has penetrated the skin, so that the exact position of the point of the needle, for example, whether the point is being maintained in the desired top or bottom position, is not known to the person inserting the needle. Moreover, since the needle must be inserted into the skin at an acute angle, allowance must be made when inserting the needle for the oblique movement of the needle and this introduces further difficulties in locating the needle exactly in a particular vein.